Student will learn:4 periodic trends :

atomic radii trend

ionization trend

electronegativity trend

reactivity trend

Periodic Trends

Atomic Radius

Ionization Energy

Electronegativity

Reactivity

½ distance between nuclei of identical atoms that are bonded

Energy required to remove one electron

Atom’s ability to gain an electron.

Atomic RadiiPeriod trends

Trend to larger radii because proton pull is less on e- of same energy level

Group trends Trend to larger atomsbecause e- are added to

NEXT energy level … farther away from nucleus.

Which has largest atomic radii? Mg, Cl, Na, P,

Which has largest atomic radii?

Ca, Be, Ba, Sr?

Which has smallest atomic radii? Li, O, C, F ?

88888 Octet rule• Chemical compounds tend to form so that each atom

has an octet of electrons in its highest occupied energy level. …

• ….atoms will try to get a group of 8 electrons in its outer orbit….

• Either by gaining,

losing,

sharing electrons

Ion = an atom or group of bonded atoms that have a + or – charge.

lost an electron = postive……Na+ cation

gain an electron =negative…Cl- anion.

• Do oxidation numbers here

Radii of IonsPositive Cations lost e- ….

» Lost therefore radii smaller

Negative Anion gained e- ….» gained therefore radii larger.

Describe the ion radii of the following as

increase or decrease.

Cl, N, Ca, Cu, S, Na,

Ionization energy energy required to remove one electron

energy required to make it a cation Period trends

Increases across

period because more

protons pull greater on

e- in same energy level

Group trends Increases going

up group. Electrons are closer to

nucleus so protons pull electrons

Tighter therefore takes more energy

to take an e-.

Measured in k/joules

1st Ionization = energy required to remove 1st electron.2nd ionization = energy required to remove 2nd electron.3rd ionization = energy required to remove 3rd electron.

“numbers will increase” “Arrange the following in increasing ionization energy.”

Li, O, C, K, Ne, FK,Li,C,O,F,Ne

Be, Ba,Ca,MgBa,Ca,Mg,Be

Which would least likely form?Sr2+, Al3+, K2+

K2+

Electronegativity ability to gain electrons ability to become an anion

Period: increases

across period b/c

octet rule is being filled

Group: increases going

up b/c electron closer

to pull of protons

Which element would gain e- easier? Br, I, Cl, F

Which element is most electronegative?

C, N, O, Se, S

• Reactivity

Which would react easier with chlorine?

Na or K

How about Sodium and Magnesium?

If Li and K and Br were mixed in a beaker. What compound would be the largest percentage?

1. In a given group lowest first ionization energy is

a. Noble gas

b. Halogens

c. Alkali metal

d. Alkaline earth metals

2. Which element has an ion with a radius

that is larger than its atomic radius?

a. K

b. Cr

c. Zn

d. Cl

3.Which element in period 3 has the greatest tendancy to gain electrons?

a. Ar

b. Cl

c. Si

d. Na

4. Arrange the following in

increasing order of atomic radii.

a. Al, Si, P

b. Li, Na, K

c. I, Br, Cl

d. N, O, F

5. Which particle has the smallest radii?

a. Na

b. K

c. Na+

d. K+

6. Which element would be the most reactive with water?

a. Au

b. Mg

c. Fe

d. Na

Student will learn:4 periodic trends :

atomic radii trend

ionization trend

electronegativity trend

reactivity trend